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U0694 Lost Communication With Hybrid/EV Battery Pack Coolant Pump A

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modePossible

Liquid-cooled traction batteries rely on an electric pump to move coolant through the pack, and pumps like Bosch's PCE accept their speed command by PWM or LIN and report faults themselves. U0694 records that battery pump A no longer communicates. Published manufacturer data do not mention it. GM's hybrid table 19OBDG01 drives its battery pump by a discrete or PWM line and judges the line current (under 200 mA or over 3 A, 4 s within 5 s, Type B), so faults surface as P0C47. Hyundai uses its own U1118 for the battery pump on the 2019 Kona Electric; campaign T4G traced it to coolant entering the pump's electronics housing and replaces the housing or the pump. Expect reduced power, slower charging and a hybrid or EV warning.

Likely causes

Coolant entered the pump electronics housing

Bus, supply or ground wire to the pump damaged

Pump motor or controller failed

Battery or hybrid controller software fault

Symptoms

Hybrid/EV system warning
Reduced drive power
Slower DC fast charging

Repair estimate

DifficultyHardWorkshop job

Parts and labour€100–900

Time1–4 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

hv battery coolant pump avehicle bus wiring

References: gsi.ext.gm.com, static.nhtsa.gov, bosch-mobility.com.